Not Applicable
1. Field of the Invention
This invention relates generally to tow bars, and more particularly to a tow bar apparatus that allows the towed vehicle a great range of motion relative to the towing vehicle while still providing a strong connection between the two vehicles.
2. Description of Related Art
Tow bars that bolt directly onto a towing vehicle for towing a towed vehicle also well known in the prior art. Examples of such tow bars are shown in Parent, U.S. Pat. No. 5,765,851, and Johnson, U.S. Re. Pat. No. 35,482, which are described in greater detail below. While these tow bars are superior to a ball hitch, these tow bars are both bulky and relatively expensive to manufacture. To provide the flexibility necessary to allow the towed vehicle a range of motion relative to the towing vehicle, most prior art tow bars include three hinged connections, one hinge providing flexibility in the horizontal plane, a second hinge providing flexibility in the vertical plane, and a third hinge that provides a pivotal point for twisting. While these hinges are functional, they are also weak points in the tow bar that could break under rigorous conditions.
It is also known to substitute at least one of the hinged connections with a ball-and-socket connection. Examples of this are shown in R. E. Moore, U.S. Pat. No. 2,139,970 and J. E. Powell, U.S. Pat. No. 1,185,435. Moore teaches a tow bar that uses three ball-and-socket connections similar to the present invention; however, Moore does not teach ball-and-socket connections that are similar to the present invention. In Moore, the ball-and-socket connections are designed to be permanent, and the sockets are removably attachable to the vehicles. This is not a structurally reliable configuration. The novel ball-and-socket connections disclosed in the present invention enable the tow bar to be even stronger and more reliable than prior art tow bars, and yet still easily removable when not in use.
Powell teaches a similar tow bar that only uses a single ball-and-socket connection. Powell suffers from the same disadvantages as Moore, and does not provide the strength required in combination with the easy disconnection of the ball-and-socket connection.
W. W. Cushman, U.S. Pat. No. 2,916,301, teaches warehouse tractors and the like and has for its primary object to so modify the pusher plate on such vehicles that the latter may be readily connected together as a train and be pulled to and from the place of work by a leading vehicle. While Cushman teaches the use of a pair of bars that terminate in hemispheres that can be joined to form a single unit, the hemispheres of Cushman are not positioned within a ball-and-socket connection. In Cushman, the hemispheres are part of a jack mechanism that merely push against a half-socket for the purposes of depressing the drawbar tongue and raising the tractor. Cushman does not teach the combination of two hemispheres within a complete socket to form a ball-and-socket connection that can withstand both pushing and pulling forces.
W. La Hodny, U.S. Pat. No. 2,071,883, teaches a ball-and-socket connection that is somewhat similar to the present invention; however, this reference is in the field of rear view mirrors. To the extend Hodney is instructive of the present invention, it would not be obvious to apply the teachings of this field to the field of towing vehicles. Rear view mirrors must be adjustable in all three dimensions, but they do not have to be very strong. Designs that might be highly adjustable, and functional for rear view mirrors, would not often be capable of withstand the rigorous pushing and pulling strains that are placed on a tow bar apparatus.
Parent, U.S. Pat. No. 5,765,851, teaches a storable self-aligning towing assembly which allows universal pivoting about three axes between a towing vehicle and a towed vehicle. The towing assembly is self-supporting. A hitching member is releasably attached to a towing vehicle at a first end of the hitching member; a first yoke member is pivotally attached to a second end of the hitching member such that the first yoke member pivots about a first axis which is generally horizontal and is normal an extended longitudinal axis of the hitching member; a second yoke member is connected to the first yoke member such that the second yoke member is free to rotate with respect to the first yoke member about an axis that is generally parallel to an extended longitudinal axis of the hitching member; a towed vehicle attachment means is releasably attached at a first end to a towed vehicle; the towed vehicle attachment means is pivotally attached to the second yoke member such that the second yoke member pivots with respect to the towed vehicle attachment means about a second axis which is generally vertical axis and is normal to the extended longitudinal axis of the hitching member. The configuration allows the towing assembly to pivot from a towing position to a storage position on the rear of the towing vehicle. A latching mechanism secures the self-aligning towing assembly in the storage position on the rear of the towing vehicle. The self-aligning towing assembly may be further converted into a shipping position.
Johnson, U.S. Re. Pat. No. 35,482, teaches a towing hitch including a frame having a forward portion selectively connected to the receiver hitch of a towing vehicle, and a rearward portion having a pair of elongated bars pivotally connected thereto for removable connection to a vehicle to be towed. Each bar has a pivot arm connected to the rearward end thereof, said pivot arms and bars all to the rearward end thereof, said pivot arms and bars all pivotal within a single plane, so that the pivot arms may be folded into a storage position adjacent and parallel to the bars. Selective locking apparatus permits the pivot arms to be extended to a towing position aligned with the bars and locked in the towing position. The bars are pivotally connected to a pivot block which is pivotally mounted to the forward portion of the frame, so as to permit the pivot block, and attached bars and arms to pivot from a generally horizontal position to a generally vertical storage position. The pivot block is mounted on a rotatable yoke, such that the bars and pivot arms are rotatable, as a unit, along an axis parallel to the direction which a vehicle is being towed.
Hobrath, U.S. Pat. No. 5,909,887, teaches a sulky for a self propelled lawn mower, the sulky being interconnected by a pivot frame and a horizontal pivot to the mower frame, and a vertical pivot between the sulky frame and wheels in order to retain the operator in a constant position in respect to the mower under all operator conditions.
The prior art teaches tow bars with flexibility between the towed and towing vehicle. However, the prior art does not teach a tow bar having three ball-and-socket connections that allow a towed vehicle a great range of motion relative to the towing vehicle, while still providing a strong connection that will not break even under rigorous towing and braking conditions. The prior art does not teach the use of two hemispheres that join within a socket to form a ball-and-socket connection. The prior art also does not teach a pair of socket members that enable a removable ball-and-socket connection between the tow bar and the towed vehicle. The present invention fulfills these needs and provides further related advantages as described in the following summary.
The present invention teaches certain benefits in construction and use which give rise to the objectives described below.
The present invention provides a tow bar apparatus that allows a towing vehicle to tow a towed vehicle. The tow bar apparatus includes a hitch member, a pair of tow bars, and a pair of socket members. The hitch member is adapted to engage a tow bar receiver of the towing vehicle. The pair of socket members are adapted to be attached to the towed vehicle. Each of the pair of tow bars includes a plate ball member at a first end for pivotally engaging one of the pair of socket members. Each of the pair of tow bars further includes a second end, the second ends of the pair of tow bars being joined to form a hitch ball member that pivotably and rotatably engages the hitch member.
A primary objective of the present invention is to provide a tow bar apparatus having advantages not taught by the prior art.
Another objective is to provide a tow bar apparatus that allows the towed vehicle a great range of motion relative to the towing vehicle, without weakening the strength of the tow bar.
A further objective is to provide a tow bar apparatus that includes a pair of tow bars, each of the pair of tow bars having a hemisphere at a second end, the two hemispheres being joined within a hitch socket member to form a ball-and-socket connection.
A further objective is to provide a tow bar apparatus that includes a pair of socket members that enable a removable ball-and-socket connection between the tow bar and the towed vehicle.